The present invention generally relates to a storage system configured from a host computer, a storage apparatus and a management computer, and to a storage subsystem storing information associated with access from the storage system and the host computer, and in particular to technology for acquiring the status of copy pairs configured with the storage apparatus.
The importance of nondisruptive operation and data protection in corporate information systems is ever-increasing due to the globalization of markets and the provision of 24/7 services via the Web. Nevertheless, there are numerous risks such as terrorism and natural disasters that may lead to the disruption or data loss of corporate information systems. In order to reduce these risks, it is necessary to assume that such disasters or failures will occur, and to plan in advance by when and how to restore the system that is shut down during the disaster or failure. This is known as “Disaster Recovery,” and will be hereinafter referred to as “DR.”
With DR, it is important to preliminarily set forth indexes indicating which data at what point in time is to be recovered by when, and operate the system while monitoring that such indexes are being observed. Among the foregoing indexes, the former; namely, the index showing which data at what point in time should be recovered is referred to as a “Recovery Point Objective” (hereinafter referred to as “RPO”), and the latter; namely, the index showing by when the business should be resumed after being affected by the disaster is referred to as a “Recovery Time Objective.”
Generally, a case where a volume to be copied is stored in the same storage apparatus as the foregoing volume is referred to as a local copy, and a case where a volume to be copied is stored in a different storage apparatus than the foregoing volume is referred to as a remote copy, and this is employed in information systems demanded of high reliability. Local copy and remote copy are sometimes collectively referred to as replication. According to this replication technology, even when a failure occurs in one of the volumes and becomes inoperable, the system operation can be continued by using the data stored in the other volume.
The two volumes of a copy source and a copy destination of a replication relationship are referred to as a copy pair. Normally, a copy pair is grouped in host computer units or application units, and the copy pair is controlled and monitored in such units. A plurality of copy pairs grouped in host computer units or application units are referred to as a copy group.
Remote copy is fundamental technology for realizing DR which prepares a remote site at a location that is geographically distant from the site (local site) conducting the business, and creates the entirely same data as the local site in the remote site.
There are two types of remote copy; namely, synchronous remote copy which returns a write completion reply to the server upon waiting for the data write completion reply on the remote site side when the business host issues an I/O [request], and asynchronous remote copy which returns a write completion reply to the server without waiting for the data write completion reply on the remote site side. With asynchronous remote copy, since it is possible to suppress the influence on the business reply performance even during the bandwidth fluctuation of the network or sudden fluctuations in the business load, this is effective when installing the remote site at a great distance or when using a network line with unstable performance.
Japanese Patent Laid-Open Publication No. 2007-47892 discloses technology concerning a storage system comprising a plurality of host computers and a plurality of storage apparatuses, wherein one storage apparatus controls the copy group extending across a plurality of storage apparatuses, and acquires the copy group and the copy pair status configuring such copy group.